LAB 7

• Culture

  MO that grow on a nutrient medium
• Types of Culture

  • Pure Culture - MO in a culture medium are all of the same species
  • Mixed Culture - purposely has two or more different species of MO growing
  • Contaminated Culture - accidentally contains more than one species of MO
  • Stock Culture - pure culture of MO used as a source of supply for research
• Colony

  Visible mass of growth
• Propagation

  Transfer of a single colony as the pure culture onto a sterile medium
• Characteristics of a Bacterial Colony

  • Size
  • Shape
  • Color
  • Texture
  • Height
  • Edge
• Characteristics Features of the Colonies - Surface of Colony

  • Mucoid - mucus like and shiny
  • Smooth - dull appearance
  • Rough - coarsely granular
• Characteristics Features of the Colonies - Elevation of Colony

  • Effuse - thin, spreading
  • Flat - thin, hardly raised
  • Raised - thick top, surface is flat
  • Umbonate - umbrealla like
  • Convex - dome-shaped and raised
  • Crateriform
• Characteristics Features of the Colonies - Opacity of Colony

  • Opaque
  • Transluscent
• Characteristics Features of the Colonies - Formation of the Colony

  • Filiform
  • Spreading
  • Arborescent
  • Punctiform
  • Beaded
• Characteristics Features of the Colonies - Amount of Growth of the Colony

  • Luxuriant - exceeds beyond expected
  • Moderated
  • Scanty
• Characteristics Features of the Colonies - Consistency of the Colony

  • Membranous
  • Viscous
  • Friable
  • Butyrous
• Characteristics Features of the Colonies - Edges

  • Entire - no indentation
  • Undulate - wavy
  • Crenated - cut rounded scallops
  • Fimbriate - narrow border
  • Curled - coil
  • Lobate
• Characteristics Features of the Colonies - Shape/Form

  • Circular
  • Irregular
  • Rhizoid
  • Filamentous
• Characteristics Features of the Colonies - Pigmentation/Color

  • White, yellow, green, etc.
• Pure Culture

  Isolation technique introduced by Joseph Lister in 1878 to isolate bacteria from milk as Bacterium lactis
• Robert Koch

  Introduced techniques of pure isolation and use of agar, isolated pure cultures from patients with pulmonary tuberculosis (Mycobacterium tuberculosis or Koch's bacillus), Bacillus anthracis for anthrax and Vibrio cholerae for cholera
• Pure Culture Isolation Techniques

  • Isolation using Selective Culture Media - Useful in the cultivation of particular bacterial species by inhibiting the growth of unwanted microbes, Contains inhibitory substances that prevent the growth of either gram+ or gram- bacteria with the exception of specific bacteria to be cultivated
  • Pour Plate Method - Involves thinning down the organisms as they are transferred from one tube to another, May be done using loop or by preparing serial dilution of the sample culture
  • Spread Plate Method - Involves spreading the sample using a sterile L-rod on the surface of the plated culture medium, Allows quantification of the bacteria per volume of the sample inoculated in the medium
  • Streak Plate Method - Involves the inoculation of the sample using the multiple interrupted streak method, Streaking results in dilution gradient of the organisms inoculated over the surface of the agar, Provides the advantage of economy of time and material, Requires skill in streaking